Method of making tire molds



July 12, 1932. R. c. BATEMAN METHOD OF MAKING TIRE MOLDS Filed March 13, 1950 amnion Riflph C.Ba\eman larly in perfect Patented July .12, 19 32 RALPH G. BA'IEHAN, OF AKRON, OHIO, ASSIGNOR TO COMPANY, OF AKRON, OHIO,

THE GOODYEAR TIRE & RUBBER A CORPORATION OF OHIO .HE'IHOI? OF MAKING TIRE HOLDS Application filed March 13, 1930. Serial 110. 435,478.

This invention relates to a, method of making molds and it has particular relation to a novel method that is especially applicable to the production of pneumatic or solid tire 6 molds.

An object of the invention is to provide a method of making molds in-which the tread design and lettering are produced without the necessity of machine work.

Another object of the invention is to provide a method of making molds in which a core is employed that will compensate for the shrinka e in rubber during vulcanization.

One met 0d of making tire molds is by molding or forging a single piece ofsuitable metal into the form of a mold section and machining the tread design into the mold. The machining of the molds I and laborious engraving operations particug a tread design in the mold, and accordingly constitutes a majorportion of the complete mold cost.

According tothis invention a rubber tread compound is disposed in a mold section, the rubber being forced into the mold by means of section is in position. The matrix so formed is th' 11 removed from the mold and asecond core of larger dimensions is disposed within the age which'occurs during vulcanization of the rubber. Means is provided for depositing metal upon the rubber matrix and after a suflicient thickness of metal Has been deposited, the metal shell is stripped therefrom. The matrix thus formed isthen secured in molds in any convenient manner. v

For a better understanding of the inven tion, reference may now be had to the accompanying drawing forming a part of this specification, in which: a

Fig. 1 is a fragmentary cross-sectional view ustrating the manner of forming a flexible matrix for use in forming molds according to this invention;

Fig. 2 is a fragmentary cross-sectional view illustratin one form of preparing a ortion of the mol and Fig. 3 is a fragmentary cross-sectional involves tedious a core section and cured while the core matrix to thus compensate for the shrink-' which is'in contact with t e tire;

view disclosing tion of the mold which a backing applied to the poris in contact with the In practicing the invention, a tire mold 10 of ordinary construction is indentations 11 formed therein corresponding to the tread tire. A pound is configuration of a finished matrix 12 formed of a rubber com- Eeinforced about its inner circumference with rubberized fabric plies 14, the ends of which are wrapped about a bead ring l6, somewhat similar to a bead ring of a tire,

and a limiting ring 17 having tapered holes 18 therein. The rings 16 and 17, the axes of which are coincidental, and vertical with reference to the drawing, are provided to engage recesses 20 and 21 of a core 22 to which a plate 23 is secured by means of bolts 24 and wh ch is adapted to maintain the bead ring 16 in position.

The In old section 10 is disposed about the rubber compound of the matrix 12, which is forced into the tread indentations of the mold section by means of the core 22. Thematrix 12 thus formed issubjected to vul- 7 canization while the core section 22 is in position, after which th from'the 1y larger dimensions section 22 is disposed the vulcanized matrix. by 'positionin surface 27 an thence e matrix is removed core and a second core 26 of slightthan that of the core within the confines. of so This is accomplished the bead ring 16 against a securing it in position means of a plate 30 after which the ring b 171s drawn against a surface 28 of bolts pered holes 18.

by means are wedged Within the ta- 7 A metal shell33 is then de- 29. that posited upon the matrix by electroplating or any convement means, such as a spraying device 34. If tro-plating,

' first coated with a thin trix 1s graphite rial the

upon whichthe metal layer can Inasmuch as this process is well electro-plating art, it will'not with further.

than the core 22 the metal is deposited it will be understood that the malayer of or similar electro-conductive matebe plated. known in be dealt The core 26 is made larger in order to stretch the matrix and thus compensate for shrinkage which.

occursfr om vulcanization of rubber. After provided having 55 y elecmetal shell upon the matrix,

the sufiicient thickness ofmetal has been deposited uon a matrix, the metal shell is stripped erefrom and, in order to increase the n 'dity of the shell, it is rovided with a backing 36 of metallic alloy aving a relatively low fusion point. A matrix thus formed is then secured in molds in any convenient manner.

I Although I have illustrated but the preferred forms of this invention and have described those forms in detail, it will be apparent to those skilled in the art that the invention is not so limited but that various -minor modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

What I claim is: 1. A method of making molds-which comprises forming a matrix about a core, vulcanizing .the matrix, dis osing the matrix about a core of a size s cient to compensate for shrinkage of the matrix, and forming a metal shell upon the matrix.

2. A'method of making molds which comprises forming a matrix about a core, vulcanizing the matrix, disposing the matrix about a core of a size sufiicient to compensate for shrinkage of the matrix, forming a removing the shell from the matrix, and applying abackin of metal thereto. I

n witness whereof, I have hereunto signed my name. v 35 Si edat Akron, in the county of Summit and tate of Ohio, U. S. A., this 7th day of March, 1930.

- 7 RALPH C. BATEMAN. 

